Method of filling explosive devices



Dec. 5, 1944. r T. E. ARNOLD ETAL METHOD OF FILLING EXPLOSIVE DEVICESFiled Dec. 31, 1941 2 Sheets-Sheet 1 mVENTORS TEARNOLD C- D O B LL WATTORNEY FIG. 2

1944 T. E. ARNOLD ETAL 2,364,415

METHOD OF FILLING EXPLOSIVE DEVICES Filed Dec. 31, 1941 2 Sheets-Sheet 2\NVENTORS 11E. AR N OLD C.D O B E LL. ATTORNEYS Patented Dec. 5, 1944UNITED FATE METHOD or FILLING EXPLOSIVE mzvicss MassachusettsApplication December 31, 1941, Serial No. 425,251 In Canada November 29,1941 2 Claims.

This invention relates to the filling of explosive devices withexplosive materials, the term "explosive devices" being intended tocover artillery shells, aerial bombs, trench mortar bombs, and

other types of bombs, anti-tank mines, depth charges, torpedo warheads,and all other explosive devices including a shell or casing containingan explosive charge. Consequently, while the present description of theinvention deals more particularly with the filling of bombs andartillery shells, it Will be understood that the invention is notlimited to these applications.

The conventional method of filling the casing of a shell or the likewith Amatol (a mixture of TNT and ammonium nitrate) and similarexplosive material consists in depositing successive charges of suchmaterial in the casing and subjecting each charge to a tamping downoperation before introducing the next charge. The explosive material isdeposited in the casing in a heated fluid, semi-fluid, or pastycondition and tends to freeze or set quickly when it strikes therelatively cool metal of the casing. It must therefore be broken down bya tampin operation to eliminate cavitiesand to ensure complete fillingof the casing with an explosive charge of the required weight ordensity. In some cases the explosive material, after being introducedinto theshell casing, is subjected to hydraulic pres sure to increasethe density of the charge. The conventional procedure here referred tois slow and tedious and is also characterized by various otherdisadvantages, some of which maybe summazized as follows:

(1) With present methods of filling shell, bomb or other casings with"Amatol there is an appreciabl time interval between commencement of themixing operation and commencement of the fillin operation: Consequently,in order to prevent excessive cooling down and contraction of theexplosive mixture prior to the filling operation it is necessary thatboth the TNT and ammonium nitrate be heated to a temperature of about190 F. to 200 F. before being mixed together to form the explosivecharge. Aside from requiring a considerable amount of heat thisprocedure increases the contraction of the mixture during subsequentcooling thereof within the shell or other casing into which it isintroduced during the filling operation.

(2) Another objection to present methods is that the so-called lean"Amator mixtures cannot be used satisfactorily without resorting to veryexpensive equipment. By "lean Amatol mixtures" is meant mixtures inwhich the proportion of TNT to ammonium'nitrate is relatively smallsuch, for example, as /20 "Amator mixtures in which the major proportionconsists of ammonium nitrate.

(3) When the explosive material is introduced into a shell or casing inthe form of a semi-fluid or pasty mass, the tamping down operations,even when followed by hydraulic pressing, do not always give a fillingwhich is of satisfactory density.

(4) The mixing and heating of the explosive ingredients and the fillingof the casings must be carried out on the batch operation principle.

(5) The mixing and heatin of the explosive ingredients requiresconsiderable time and involves the use of expensive and inconvenientapparatus including various moving parts and valves which frequentlygive trouble due to breakage and other causes.

(6) The method of mixing and heating the ingredients of the explosivecharge is wasteful of heat and requires that an appreciable amount oftime be allowed for subsequent cooling of the charge.

(7) The maximum explosive efiect of the charge is not always realizedowing to the imperfect distribution of the component ingredients.

(8) The method of filling does not lend itself' to the proper filling ofcasings in which the cavity and the filling openings are of suchrelatively small dimensions as to prevent efiective tamping down orpressing of the charge.

According to our invention the foregoing objections are eliminated bythe provision of what may be termed a continuous pressur injectionmethod of filling explosive devices. When this method is used forfilling explosive devices with Amatol or other explosive mixtures whichare formed by mixing a dry component with a liquid component it enablesthe mixing and filling operations to be carried out in a continuousmanner, the dry and liquid components being continuously and separatelyfed, under pressure, to a mixing chamber from whence the resultingmixture is immediately discharged, under pressure,

' into the cavity of the shell or casing to be filled.

It will thus be seen that, with this procedure, there is no appreciabletime interval between the mixing of the dry and liquid components andthe pressure injection of the resulting mixture into the cavity to befilled. This makes it feasible to heat only the liquid component of thecharge and to convey the dry component to the mixing chamber in a coldcondition. For example, in the case of "AmatoP it is feasible to supplythe ammonium nitrate in a cold, dry'condition' to a mixing chamber whereit is mixed with hot liquid TNT so that the resulting mixture isdischarged into the cavity to be filled before there is any substantialcooling or contraction thereof. This not only saves heat as comparedwith the usual procedure of heating both the TNT and ammonium nitratebut also reduces the contraction of \the charge during subsequentcooling thereof in the cavity of the shell.

A very important advantage of our novel process is that it requires themixing at one time of only a small amount of explosive mixture, and suchmixing takes place in the mixing chamber of a nozzle located closelyadjacent to the shell being filled. Therefore any explosion would belimited to the mixture in the nozzle and in the shell, and would involveno large amount of previously prepared explosive mixture, as must be thecase in loading practice heretofore.

Another advantage of the procedure described herein is that it readilylends itself to the use a of very lean Amatol mixtures since the mixingof the two ingredients. TNT and ammonium nitrate, is immediatelyfollowed by injection of the mixture into the cavity to be filled.

A further advantageof our improved method is that it results in anexplosive charge which is of substantially greater density as comparedwith conventional methods of filling. It also lends itself to a'more satsfactory distribution of the component ingredients throughout the massof the charge andthus increases the explosive efiect.

Another feature of the invention consists in utilizing compressed air toconvey the dry component of the explosive charge to the mixing chamberwhere it is mixed with the hot liquid component which is pumped to themixing chamber under pressure, the compressed air being also utilized toblow the hot explosive mixture from the mixing chamber into the cavityof the shell or other explosive device to be filled. For example. whenthe explosive charge to be formed and introduced into the cavity to befilled is "Amatol the ammonium nitrate in a cold dry state is entrainedin a stream of compressed air which is forced through the mixing chamberand into the cavity to be filled. Hot liquid TNT is simultaneouslypumped to the mixing chamber where it is mixed with the dry ammoniumnitrate, the resulting homogeneous mixture being immediately blownthrough the outlet of the mixing chamber and directly into the cavity tobe filled. This procedure may be followed not only in cases where solidand liquid components are to be brought together to form the explosivecharge but also in any cases in which two different ingredients or twocomponent parts of the explos ve material are to be mixed together toform the final charge which is to be introduced into the cavity to befilled.

A further feature of the invention consists in efiecting pressureinjection of an explosive charge into the cavity of a shell. bomb, orother casing while rota ing said casing at a sufficient rate of speed toeffect a desirable centrifugal distribution of t e explosive materialwithin said casing. In practice we have'found that. when the casingbeing filled is rotated at a suitable speed during the fillingoperation, the centrifugal force developed in the mass of liquid orsemi-liquid explosive material introduced into the casing tends toensure a better dispersion or distribution of the component ingredientsof they mass and a greater density of the charge.

In the case of Amatol and similar explosive charges, including a liquidcomponent, a further feature of the invention consists in decreasing thesurface tension 'of the liquid component by adding thereto a suitablesurface tension decreasing chemical or wetting agent such, for example,as Aeresol. In practice, when Amatol and similar explosive charges areinjected into the cavity to be filled in accordance with our pressureinjection method, a better dispersion of the component ingredients ofthe char e may be obtained when the surface tension of the liquidcomponent of the charge is decreased as here suggested.

Proceeding now to a more detailed description of this inventionreference will be had to the accompanying drawings, wherein- Fig. l is aview illustrating a preferred application of the invention to thefilling of the cavity of a bomb.

Fig.2 is a plan view of the adapter and filling nozzle shown in Fig. 1.

Fig. 3 is a view illustrating a modification of the invention in which aplurality of small nozzles are employed for introducing the explosivematerial into a cavity having a relatively small filling opening. ,7

Fig. 4 is a plan view of the nozzle arrangement shown in Fig. 3.

Fig. 5 is a View illustrating a further modification of the invention inwhich a single nozzle of special design is employed for introducing theexplosive material into a cavity having a relatively small fillingopening.

Fig. 6 is a bottom plan view of the nozzle shown in Fig. 5.

Fig. 7 is a view illustrating one arrangement which may be used forrotating a bomb, shell or other casing during the filling thereof inaccordance with this invention.

In Fig. 1 of the drawings our invention is illustrated as applied to thefilling of a conventional bomb casing 5 presenting a cavity 6 and athreaded filling opening I. The mixing nozzle 8 herein illustrated hasan outer casing which tapers from a central zone of maximum diameterupwardly to an inlet or entrance passage I3 and downwardly to an outletor discharge passage 9. In this case the explosive charge is formed bymixing a cold. dry, granular or powdered component with a hot liquidcomponent within the nozzle 8 from whence the resulting mixture isimmediately blown or forced into the cavity 6 through the nozzle outlet9. The" liquid component of the charge is pumped through a liquid lineit to an internal annular chamber l I of the nozzle 8, said chamberbeing located in the widest part of the nozzle intermediate thedischarge end 9 and the entrance end I3 of the main nozzle passage l4and being provided with openings IS in thewalls of the passage I throughwhich the liquid passes into said main passage M. The dry componentsistency of the mixture thus obtained may, of

course, be regulated by varying the ratio of the discharge end 9 liquidto the dry component. The' portion of the nozzle lying between thechamber II and the is preferably provided with bailies or ridinggenerally indicated at 8a which assists by a turbulent action ineffecting the necessary mixing to ether of the liquid and drycomporients of the charge.

In the present case it will be assumed that the explosive charge is tobe formed by mixing together within the nozzle 8 liquid TNT(trinitrotoluol) and dry ammonium nitrate. In this case hot liquid TNTis pumped to the nozzle through the liquid line l0 and the latter ispreferably provided with a steam jacket lfla into which steam isintroduced to p ev t oo of the TNT on its way to the mixing chamber ofthe nozzle. The ammonium nitrate is introduced into the compressed airline IS in a cold dry condition. The consistency of the resulting chargewill depend on the relative proportions in which, the two ingredientsare mixed together and this may be varied within very wide limits.

As previously stated, a suitable chemical may be added to the hot liquidTNT to decrease the surfacetension thereof since this tends to ensure abetter dispersion of the ingredients of the explosive charge within thecasing or cavity into which it is introduced.

The arrangement shown in Fig. 1 may also be used for the mixing andpressure injection of explosive charges consisting mainly of TNT with asmall amount of binder such as beeswax. In this case the beeswax will bemelted and supplied through the line H] as the liquid component of themixture to be formed, the TNT being supplied in the solid state throughthe compressed air line '6. Similarly, TNT biscuit may be suppliedthrough the compressed air line it to the nozzle 8 and there mixed withliquid TNT supplied through the liquid line Hi. It will thus be seenthat the invention lends itself to the continuous preparation andinjection of various explosive mixtures involving the mixing of liquidand solid components.

In using the apparatus described herein it is, of course, important thatthe air and liquid pressure be suitably regulated to give the requiredvelocity to the mixture at the mixing nozzle 8. The consistency of themixture formed within the mixing nozzle 8 depends. of course, upon therelative amounts of dry and liquid explosive material supplied throughthe lines I6 and ill. The amount of dry explosive material suppliedthrough the line l6 should therefore be carefully regulated in relationto the amount of liquid supplied through the line 10, the latter beingregulated by a suitable valve lllb. We have not thought it necessary toshow the machine or apparatus for controlling the supply of dryexplosive material through the line 16 but it will be understood thatthis may be accomplished in various ways.

In the case of bombs. shells and other explosive devices it is necessarythat a cavity be provided in the explosive charge adjacent the fillingopening of the casing to accommodate the conventional exploder tube.When following the conventional method of filling, the casing is filledwith the explosive material and, when the latter has solidified, it isdrilled or cored to provide the necessary cavity for the exploder tube.When the filling; is carried out in accordance with the presentinvention it is'possible to fill the casing in such a way that theexploder tube cavity is formed during the filling operation. In thisconnection it will be noted that, as shown in Fig. 1, a cavity formingadapter 20 is inserted in the filling opening 1 of the casing 5. Thisadapter comprises a ring 2! which overlies and protects the threads ofthe opening 1 and which is supported in place by an outwardly directedflange 22 which rests on the upper end of the bomb casing. A centrallydisposed cavity forming tube 23 is supported from the ring 2! byradially extending spokes or spider arms 24. During the fillingoperation the discharge end of the nozzle 8 is directed downwardlybetween two of the spokes 24 and the hot explosive mixture is forcedinto the casing 5 until it fills the casing to approximately the levelof the upper end of the cavity forming tube 23. When the explosivematerial has cooled and solidified the adapter 20 is removed and thetube 23 may or may not be left in place Within the cavity 23a.

When the filling opening of the casing 5 is relatively small as shown inFig. 3 the single nozzle 8, described in connection with Fig. 1, isreplaced by a plurality of small nozzles B which are of the sameconstruction. Th small nozzles 8 shown in Fig. 3 are positioned betweenthe spokes 24 of the adapter 20 which corresponds to the previ ouslymentioned adapter 20 except that it is considerably smaller in size.

In Fig. 5 we have shown a single nozzle 8 which is provided with anannular discharg outlet 80. In this case the annular discharge outlet ofthe nozzle is placed on the spokes or spider arms 28 of the adapter 20so that the upper end of the forming tube 23 lies within the circleformed by the inner cylindrical wall of said annular outletwhich issupported by radial spokes within the barrel of the nozzle as shown inFig. 6. In this case the explosive material is discharged from thenozzle in the form of an annular stream encircling the cavity formingtube 23.

In Fig. '7 we have shown one method of rotating a bomb shell or othercasing during the filling operation but it will be understood thatvarious other methods and arrangements may be resorted to foraccomplishing the same purpose. As shown in Fig. 7, the casing 5 ismounted on a turn-table 28 and is caused to rotate with said table bymeans of suitable holding means generally indicated at 29. The table 28is carried by a supporting shaft 30 which, during the filling operation,is rotated at a suitable speed by means of a motor or other means (notshown). The speed of rotation of thetable 28 and casing 5 should be suchas to develop an appreciable centrifugal force within the mass of theexplosive charge which is introduced into said casing through thepressure injection nozzle 8. 4

Our novel and improved method of filling casings as herein describedwill now be clearly apparent from the above description taken inconnection with the accompanying drawings. Compressed air is forcedthrough the nozzle 8 from the conduit [6 together with the proper amountof dry explosive which is added to the air stream '1 before mixing theliquid explosive and ingredients therewith. Detonating efi'iciency ofthe charges is dependent upon various factors, among which the intimatemixing together of the ingredients and the density of the charges are ofgreat importance. Our invention contemplates the effective achievementof the first of these factors by a thorough intermingling of theingredients in the mixing chamber 8 where the liquid explosive and otherliquid ingredients are projected under pressure transversely into theair-conducted 4 v j stream of dry explosive, the liquid preferably beandfrom which they are continu'ouslyblown into.

the shell being loaded. The ingredients may be given a further turbulentand mixing action as they pass through the mixing chamber by theemployment of baffie plates as indicated at 8a. It is furthermore andparticularly pointed out that this thorough mixing action is asessential with such ingredients as wetting agents, liquid binders, etc.as with the liquid explosive itself since full and complete diffusion ofsuch ingredients is required if they are fully to perform their intendedfunctions. The density of the charge is facilitated by the thoroughmixing of the ingredients and this, together with the centrifugal actioneffected by rotating the casing at proper speed during filling, resultsin securing charges of maximum density and maximum detonatingeffectiveness.

' Having thus described what we now conceive to be the principle andseveral preferred arrangements of our invention, it will be understoodthat various modifications may be resorted to within the scope andspirit of the appended claims.

Having thus described our invention what we claim is:

1. The method of filling shell or other casings with explosive charges,which consists in continuously conducting two individual explosivecomponents of the charge, both of which are solid at room temperature,in separate streams from distant sources of supply to the vicinity ofthe shell to -be filled, and includes the steps of injecting underpressure a stream of fluid pressure carrying one of said explosivecomponents in dry granular form in suspension therein through a2,se4,41a

passage into a mixing space located adjacent to the shell, projectingthe other of said explosive components in the form of a heated liquidstream transversely and under pressure into the fluidborne stream ofgranular component in the said mixing space, thereby effecting aturbulent action intimately combiningthe said components together into ahot homogeneous mixture, continuing the movement of said stream ofcompressed air and hot explosive mixture directly and forcibly from themixing space and compactly into the casing to be filled, and solidifyingthe charge by cooling from the walls of the casing.

2.. The method of filling shells with explosive charges, which consistsin continuously conducting individual explosive components of thecharge, each of which is solid at room temperature, in separate streamsfrom distant sources of supply to the vicinity of the shell to befilled, and includes the steps of injecting under pressure a stream ofcompressed air carrying one of said explosive components in dry granularform in suspension therein in a confined stream into a mixing spacelocated adjacent to the shell and of substantially larger volume thanthe said stream, projecting the other of said explosive -components inthe form of a heated liquid in a mixture directly and forcibly from themixing space and compactly into the casing to be filled.

and solidifying the charge by cooling, at least in part, from the wallsof the shell casing.

THEODORE E. ARNOLD. CURZON DOBELL.

